Studies on the biogenesis of mitochondria and chloroplasts will be carried out using yeast mitochondria and barley chloroplasts as test organisms. The molecular events involving mitochondrial DNA following zygote formation of cells with differing mitochondrial DNAs will be studied by centrifugal and electron microscopic analysis. Restriction nuclease cleavage of mitochondrial DNAs from respiratory competent and deletion petite strains of yeast containing antibiotic resistance markers will be used in structural analysis of mitochondrial DNA. The nature of the change in ATPase giving rise to oligomycin resistance in mutant forms of yeast will be investigated. Kinetics of the assembly process in formation of active ribulosediphosphate carboxylase from the two inactive subunits will be followed in greening barley seedlings. Antibody precipitation of ribulosediphosphate carboxylase attached to polysomes from chloroplasts will be used to attempt isolation of specific messenger RNA for this enzyme.